Sleep duration represents a biological imperative that is influenced by an interaction of social, behavioral and environmental factors. Behavioral factors include habitual sleep timing as well as other socially-influenced behaviors that engage physiological processes promoting or impairing sleep. Factors in the social environment include the home, work and other social influences on an individual's sleep schedule that may or may not be line with normal biological imperatives, as well as aspects of the physical environment that may interfere with sleep. Very little research has explored the impact of health behaviors (diet, physical activity, and substance use), social factors (family status, social functioning, isolation, and stress), or the physical environment (neighborhood and sleeping environment) as pathways to reduced sleep time. In addition, studies that have examined these factors typically explored sleep using broad survey items, rather than validated methods. Accordingly, a 2-Phase protocol will be deployed to address these issues. Phase 1 involves an online survey of n=1000 adults, using validated measures to assess sleep in the context of general health (obesity, functioning and mood), healthy behaviors (diet, physical activity, and substance use) and social factors (work and home social and social demands, functioning, isolation). These individual-level data will be merged with data neighborhood-level obtained through existing geospatial databases. This will allow for evaluation of whether individual-level sleep variables are associated with area-level measures (derived using respondents' address) of neighborhood variables, including population density, socioeconomic status, social isolation, traffic, noise, an crime/violence, and whether external sources of information predict sleep duration over and above individual-level measures. Phase 2 will consist of an intensive, prospective analysis of a subgroup of n=90 from the survey sample (n=30 each of <5, 5-6, and 7-8 hours of habitual sleep). This assessment will include objective measures of sleep (wrist actigraphy), health status (e.g., body mass index, blood-based measures), physical activity (hip actigraphy), and the sleeping environment (sensors for light, temperature, and noise). Daily diaries will assess sleep, diet, physical activity, substance use, social interactions, and the sleeping environment. The overall goal of this study is to assess the relative contributions of behavior, social, and factors on sleep of environmental habitual duration, employing multimodal assessments all domains, and leveraging novel approaches, such as geospatial analyses. As insufficient sleep duration is an important public health problem, the eventual goal of developing interventions to address this problem cannot be reached until we better understand (1) which factors need to be part of an intervention, (2) where interventions should be targeted, and (3) what types of assessments capture the relevant social and environmental features. The present exploratory/developmental research study will address these important issues and initiate a program of research developing and implementing successful interventions for insufficient sleep in the general population.